The invention relates to a thin film semiconducting structure. More particularly, the invention relates to thin film semiconducting structures such as, for example, photovoltaic cells, photodetectors, and light emitting diodes. Even more particularly, the invention relates to electrodes for such thin film semiconducting electronic structures.
In many thin film semiconductor sensor and device applications, major technical difficulties arise from the lack of a suitable epitaxial template for the growth of well-oriented films. For example, photovoltaic energy conversion efficiency for solar cells based on amorphous silicon architectures seldom surpass 8% efficiency, whereas solar cells that use single-crystalline silicon can approach 24%. Conventional epitaxial film-growth techniques that are used to obtain well-oriented thin films require single-crystal templates that are usually expensive or available on a limited basis.
Biaxially oriented silicon films have been grown on flexible metal tapes by using multiple layers of insulating oxides as diffusion barriers and epitaxial templates. However, in many electronic and sensor applications, such as conventional photovoltaic cells, a conducting layer or electrode is needed under the photosensitive silicon layer to establish an electrical back-contact.
No technology exists for achieving the growth of well-oriented, biaxially oriented non-oxide semiconductors, such as silicon, on either amorphous or polycrystalline templates, with a conductive, biaxially-oriented back electrode. Therefore, what is needed is a thin film semiconducting structure having an oriented semiconductor layer and a conductive, biaxially oriented back-electrode. What is also needed is such a biaxially oriented back-electrode for such structures. Finally, what is needed is a method of making thin film semiconducting structures having such an electrode.